Cordless telephones are known to offer great mobility. A cordless telephone comprises a base unit and a handset, wherein the handset connects to the telephone network via the base unit.
In order to make wireless telephones appear seamless, some cellular telephones have been designed to operate in a dual mode wherein they operate on a standard cellular protocol when out of range of a base unit and operate as a cordless handset via a base unit when within range of the base unit.
When used with its base unit, the dual mode cellular handset communicates with the telephone network via the base unit. That is, the dual mode handset communicates with the base unit via an RF link and then with the telephone network via a standard copper wire pair from the base unit to a central office (CO) or a small business switch such as a PBX. Otherwise, when away and out of range of the base unit, the handset operates as a regular cellular telephone, wherein the user accesses the telephone network via the cellular network infrastructure.
In both of these cases, the base unit can be used as a desktop charger. It may also be provided with a keypad to enable the user to dial out or answer via the wireline network.
One problem with these cordless telephones prior art is that the base unit must be physically connected to the telephone network. That is, while the user has the advantages associated with portability, the base unit must still be connected to a central office.
With dual-mode cellular telephones, while the user has the advantages of the portability of a cellular handset when operating the handset on a standard cellular protocol, a disadvantage remains in that the base unit still requires connection to a wireline network central office. Hence, the physical convenience that these dual mode telephones introduce is limited. Also missing is the usual cost savings on physical line connections that is usually related with a standard cellular phone.
Another problem with these dual-mode telephones is that the cordless handset is only compatible with one particular base unit. This lack of flexibility means that the user of a particular handset must return to its particular base unit when wishing to communicate in a cordless mode. Furthermore, when, for example, the dual mode telephone is utilized in a work environment, there is time and expense involved each and every time an employee changes his or her office location and must accordingly have his or her telephone number follow.
Therefore a need exists for a telephone system which overcomes the aforementioned problems.